Li-S电池硫正极性能衰减机理分析及研究现状概述

由于汽车工业的持续发展, 对高能量密度二次电池的需求逐步增加, 锂硫电池开始走进人们的视野. 锂硫电池的理论比能量高达2600 Wh/kg, 而单质硫的理论比容量达1680 mAh/g. 同时, 硫的储量丰富, 廉价, 并且环境友好. 虽然可充电锂硫电池相比于传统锂离子电池有诸多优势, 但目前其可实现的实际比容量远低于理论比容量, 循环寿命也较短等弊端限制了其大规模应用. 作者从Li-S电池正极的工作原理出发, 对硫正极容量损失及衰减机理做了深刻的解析, 并结合本实验室的工作归纳总结了导致硫正极容量衰减的主要因素. 针对硫正极容量衰减因素, 从碳导电结构、聚合物包覆以及纳米金属氧化物添加剂等方面, 对近年来提高硫正极性能的主要研究方向及最新研究进展进行了综述, 并对其中存在的问题进行分析, 最后对提高Li-S电池的整体性能提出展望.     

Phytochemical,cytotoxic and chemotaxonomic study on Ajuga forrestii Diels (Labiatae)

A phytochemical investigation of Ajuga forrestii Diels led to the isolation of 14 compounds, including eight neo-clerodane diterpenes (1–8), two phytoecdysteroids (9, 11), one stigmastane sterol (10) and three iridoid glycosides (12–14). The structures of these compounds were identified by spectroscopic methods and a comparison of their data with those reported in the literature. This is the first report of compounds 1–14 from A. forrestii. The cytotoxic activities of the aqueous extract of A. forrestii and several compounds have been studied and the chemotaxonomic significance of isolated compounds has also been summarised.     

Identification of metabolites of Ginkgolide B in vivo and in vitro using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry

Ginkgolide B is a dietary diterpene with multiple pharmacological activities. However, current research on ginkgolide B is not comprehensive. The current study analyzed the metabolic profile of ginkgolide B in vivo and in vitro using ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry. To detect and identify the different metabolites in ginkgolide B, a novel data processing method was used as an assistant tool. A total of 53 different metabolites of ginkgolide B (38 phase I metabolites and 15 phase II metabolites) were detected relative to blank samples. The biotransformation route of ginkgolide B was identified as oxidation, dehydroxylation, hydrogenation, decarbonylation, demethylation, sulfate conjugation, glucose conjugation, methylation, and acetylation. The current study demonstrated a method for rapidly detecting and identifying metabolites and provided useful information to further characterize the pharmacology and mechanism of ginkgolide B. A method for the analysis of other diterpene metabolic components in vivo and in vitro was also established.     

沉积物中石英ESR测年功率饱和效应的初步研究

介绍了几组沉积物中石英ESR功率饱和效应的基础实验情况,认为在用石英进行ESR测年时,微波功率的选择是一个重要参数,它直接影响累积剂量(AD)的求取,从而严重影响测年结果。在某些特定的地质环境下(如黄土,海洋沉积物),采用比较高的微波功率,可从沉积物石英的E'心得到较老沉积物(大于50万年)可信的ESR年代。     

储存环高频剔除系统

 介绍了用于电子储存环部分填充和非均匀填充的一种实验装置,它利用储存环中电子运动所具有的横向自由振荡和束团脉冲的时间结构这一特性,采用外加激励的方法使其产生共振,从而使得储存环中部分束团中的电子丢失,形成储存环的部分填充和非均匀填充。还扼要介绍了用高频剔除系统在储存环上实现不同填充方式时的束流积累结果。     

Assessing the Apparent Effective Thickness of the Supported Hybrid Bilayer Membranes Consisting of Octadecanethiol and Phospholipid by ac Impedance Spectroscopy

The electrochemical behavior of the gold electrode modified by hybrid bilayer membranes in different concentrations of Fe(CN)₆^3?/Fe(CN)₆^4? was investigated by electrochemical impedance spectroscopy and cyclic voltammetry technology. The electron transfer between gold and the redox species separated by the hybrid bilayers assembly was completed by an electron tunneling process. A detailed equivalent circuit for electron transport across the HBMs is proposed. It was found that the apparent effective thickness of the hybrid bilayer membranes was lower than that of the sum of the chain length of octadecanethiol and phospholipid so some possible collapsed sites might exist at the hybrid bilayer membranes.     

Widely and continuously tunable optical parametric generator based on MgO-doped periodically poled LiNbO3 crystal

A widely and continuously tunable optical parametric generator (OPG) pumped by a 1064-nm acoustooptically Q-switched diode-end-pumped Nd:YAG laser based on MgO-doped periodically poled LiNbO3 crystal with a multigrating structure (29.2-30.4 μm) is reported.A broad continuous signal spectrum of 1513-1700 nm is obtained by changing the crystal grating periods from 29.2 to 30.4μm and by tuning the crystal temperature from 30 to 180 ℃ simultaneously.When the average pump power is 1.82 W with pulse duration of about 70 ns operating at a repetition rate of 10 kHz,the maximum signal output power of the periodically poled MgO-doped lithium niobate (PPMgLN) OPG is about 210 mW corresponding to the idler and total powers of 118.4 and 328.4 mW respectively.     

Fission fragment mass yields of Th to Rf even-even nuclei

Fission properties of the actinide nuclei are deduced from theoretical analysis. We investigate potential energy surfaces and fission barriers and predict the fission fragment mass yields of actinide isotopes. The results are compared with experimental data where available. The calculations were performed in the macroscopic-microscopic approximation with the Lublin-Strasbourg Drop (LSD) for the macroscopic part, and the microscopic energy corrections were evaluated in the Yukawa-folded potential. The Fourier nuclear shape parametrization is used to describe the nuclear shape, including the non-axial degree of freedom. The fission fragment mass yields of the nuclei considered are evaluated within a 3D collective model using the Born-Oppenheimer approximation.     

Visible light induced decomposition of sulfonyl hydrazides using Pd/ZrO2 nanocomposite photocatalyst

A new approach to synthesis of thiosulfonates has been developed under mild conditions without any oxidants and promoting reagents through a Pd/ZrO₂ nanocomposite photocatalyst catalyzed decomposition of sulfonyl hydrazides. This protocol gave the products in moderate yields, comparable to the best results reported so far. Finally, a plausible reaction mechanism was proposed.     

Magnetic Multi-Walled Carbon Nanotubes Matrix Solid-Phase Dispersion with Dispersive Liquid–Liquid Microextraction for the Determination of Ultra Trace Bisphenol A in Water Samples

Magnetic nanoparticle-assisted solid-phase dispersion (MMSPD) combined with dispersive liquid–liquid microextraction (DLLME) prior to high performance liquid chromatography with fluorescence detector (HPLC–FLU) is presented for determination of ultra trace Bisphenol A (BPA) in water. Magnetic multi-walled carbon nanotubes (MMWCNTs) were synthesized for the adsorption of BPA in water. Ultra trace BPA in water was transferred into the elute solvent by the MMSPD and further concentrated into trace volume extraction solvent by the DLLME. The limit of detection and limit of quantitation were 0.003 and 0.01 µg L^?1, respectively. Good linearity of BPA was found, ranging from 0.01 to 10 µg L^?1, with good squared regression coefficient (R ²) of 0.9999. Additionally, relative recoveries were 83.1 and 95.9% for two environmental water samples spiked with 0.20 µg L^?1 BPA, respectively. All results showed that the MMWCNTs nanoparticle-assisted MMSPD–DLLME–HPLC–FLU method was simple and reliable for the determination of ultra trace BPA in environmental water.